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Files Reference
Directories contain directory
entries. Each entry contains a file or subdirectory name and an i-node
(index node reference) number. To increase speed and enhance the use of
disk space, the data in a file is stored at various locations throughout the
computer's memory. The i-node contains the addresses used to
locate all of the scattered blocks of data associated with a file. The
i-node also records other information about the file, including time of
modification and access, access modes, number of links, file owner, and file
type. It is possible to link several names for a file to the same
i-node by creating directory entries with the ln command.
Because directories often contain
information that should not be available to all users of the system, directory
access can be protected. See "File Ownership and User
Groups" in AIX 5L Version 5.1 System User's Guide:
Operating System and Devices for more information.
Directories can be defined by the
system or the system administrator, or you can define your own
directories. The system-defined directories contain specific kinds of
system files, such as commands. At the top of the file system hierarchy
is the system-defined root directory. The root directory is represented
by a / (slash) and usually contains the following standard system-related
directories:
/bin
| Symbolic link to the /usr/bin directory. In prior UNIX
file systems, the /bin directory contained user commands that now
reside in /usr/bin in the new file structure.
|
/dev
| Contains device nodes for special files for local devices. The
/dev directory contains special files for tape drives, printers,
disk partitions, and terminals.
|
/etc
| Contains configuration files that vary for each machine. Examples
include:
The /etc directory
contains the files generally used in system administration. Most of the
commands that used to reside in the /etc directory now reside in
the /usr/sbin directory. However, for compatibility, it
contains symbolic links to the new locations of some executable files.
Examples include:
- /etc/chown is a symbolic link to the
/usr/bin/chown.
- /etc/exportvg is a symbolic link to the
/usr/sbin/exportvg.
|
/export
| Contains the directories and files on a server that are for remote
clients.
|
/home
| Serves as a mount point for a file system containing user home
directories. The /home file system contains per-user files
and directories.
In a standalone machine, a separate
local file system is mounted over the /home directory. In a
network, a server might contain user files that should be accessible from
several machines. In this case, the server's copy of the
/home directory is remotely mounted onto a local /home
file system.
|
/lib
| Symbolic link to the /usr/lib directory, which contains
architecture-independent libraries with names in the form
lib*.a.
|
/sbin
| Contains files needed to boot the machine and mount the /usr
file system. Most of the commands used during booting come from the
boot image's RAM disk file system; therefore, very few commands
reside in the /sbin directory.
|
/tmp
| Serves as a mount point for a file system that contains system-generated
temporary files.
|
/u
| Symbolic link to the /home directory.
|
/usr
| Serves as a mount point for a file system containing files that do not
change and can be shared by machines (such as executables and ASCII
documentation).
Standalone machines mount a
separate local file system over the /usr directory. Diskless
and disk-poor machines mount a directory from a remote server over the
/usr file system.
|
/var
| Serves as a mount point for files that vary on each machine. The
/var file system is configured as a file system since the files it
contains tend to grow. For example, it is a symbolic link to the
/usr/tmp directory, which contains temporary work files.
|
Some directories, such as your
login or home directory ($HOME), are defined and customized by the
system administrator. When you log in to the operating system, the
login directory is the current directory. If you change directories
using the cd command without specifying a directory name, the login
directory becomes the current directory.
Files,
Directories, and File Systems for Programmers in AIX 5L Version
5.1 General Programming Concepts: Writing and Debugging
Programs introduces i-nodes, file space allocation, and file, directory,
and file system subroutines.
File Systems
and Directories Overview in AIX 5L Version 5.1 System
User's Guide: Operating System and Devices introduces files
and directories and the commands that control them.
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